New L3901 HST - question on HST

[fendley]

Greetings everyone - new to the forum and just purchased a L3901 with LA525 loader, and BH77 backhoe. I have been reading on the forum, and have constructed a dolly for the BH to aid in removing and installing the BH -works great.

I have a question on the normal operation of the tractor.

I have an old, grey-market L1501, so this new tractor is very different. There is a lot of hydraulic noise and whining from the HST both in and out of 4WD - is this normal? The tractor operates great, although it bogs a lot more going up steep hills, as compared to my little tractor. I guess this is to be expected on a 5000+ lbs tractor.

 

[nickelplated5s]

If it doesn't already have SUDT switching to it will quiet it some but that pump is going to make some noise. Try switching 'gear' or range for the hill.

 

[TripleR]

Mine has gotten quieter over time and can be mitigated by making sure to use the proper range and pedal setting, try backing off the pedal a bit or increase the RPM.

 

[fendley]

Thanks for the input, both of you mentioned the proper selection of the range. In the case where I had an issue, I was driving up the mound for my septic system, which rises about 3 feet over a distance of less than 5 feet, so it is pretty steep. I was in the Hi range, so shifting to M or L definitely makes sense.

What is SUDT, an additive like a friction modifier?

 

[OldeEnglish]

Thanks for the input, both of you mentioned the proper selection of the range. In the case where I had an issue, I was driving up the mound for my septic system, which rises about 3 feet over a distance of less than 5 feet, so it is pretty steep. I was in the Hi range, so shifting to M or L definitely makes sense.

What is SUDT, an additive like a friction modifier?

Kubota Super UDT hydraulic fluid

 

[fendley]

Kubota Super UDT hydraulic fluid

Thanks OldeEnglish.

 

[North Idaho Wolfman]

And the proper fluid to change to is SUDT2, that is full synthetic, SUDT is semi synthetic and will not quite it down much.

 

[fendley]

And the proper fluid to change to is SUDT2, that is full synthetic, SUDT is semi synthetic and will not quite it down much.

So if I read the WSM correctly, the Transmission Oil Filter gets changed at the 50 hours point (then every 200 hours after that), would that be the time to change to the SUDT2? The procedure for the Transmission Oil Filter change only describes topping off the fluid, while the service interval for the transmission fluid is 400 hours.

 

[D2Cat]

Fendley, if you're suggesting you're operating your L3901 on top of your septic tank, be aware you could be in for a sudden surprise when you least expect it.

The lid on our tank fell in and we only had wood chips and decorative stone on the edge. Never walked on it, or rode any kind of a lawn mower across it. Just flat failed!!

 

[North Idaho Wolfman]

The sooner you change the oil out the sooner you will get quiter performance.

You didn't say how many hours you have on it now, if it's still very new wait untill you need to change it for the first time to save cost.

 

[fendley]

Fendley, if you're suggesting you're operating your L3901 on top of your septic tank, be aware you could be in for a sudden surprise when you least expect it.

The lid on our tank fell in and we only had wood chips and decorative stone on the edge. Never walked on it, or rode any kind of a lawn mower across it. Just flat failed!!

Not really the septic tank, but the septic drain field mound. Here in south GA, the drain field goes to a mound of septic sand - in my case 40 feet wide and 65 feet long. The idea is that the water goes into the sand, and evaporates, since the mound is above grade level. There is also nylon separators below the pipes that prevent the water from seeping into the ground.

 

[fendley]

The sooner you change the oil out the sooner you will get quiter performance.

You didn't say how many hours you have on it now, if it's still very new wait untill you need to change it for the first time to save cost.

4 hours on it so far, so I'll wait until the 50 hour filter change. Thanks.

 

[CaveCreekRay]

fendley,

High range is basically a level ground travel range. If you are negotiating any hills to speak of, you should be in mid-range. Any time you travel in high range, get the power up to the PTO mark as that is the peak of your torque for your motor. You can carry a full bucket of material in HIGH but only on fairly level ground. If you are doing a lot of starting and stopping, use MED or LOW.

The super high "water pressure" sound you hear is the HST valves bypassing under load. If the load is not too high, the tractor will accelerate and that noise will be replaced by the regular noise of the HST. There is one valve for FWD and one valve for REV. It doesn't bypass much in MED or LOW range so you don't hear it.

I just had both valves replaced under warranty as they were bypassing more than they should. I think the previous owner did everything in HIGH which probably wore them out.

The first time I drove my machine I thought the tranny was about to explode. My L-3800 and your 3901 has almost 40hp. That takes a fairly large HST to handle the loads. Big tranny=Big noise. I too hope to quiet it down some when I swap to synth fluid. (If I remember correctly, the CASE 580D backhoe I ran after college only had a 45hp motor.)

In the meantime, get some good headphones. I wear the ones with a radio built in.

Welcome.

Ray

 

[fendley]

fendley,

High range is basically a level ground travel range. If you are negotiating any hills to speak of, you should be in mid-range. Any time you travel in high range, get the power up to the PTO mark as that is the peak of your torque for your motor. You can carry a full bucket of material in HIGH but only on fairly level ground. If you are doing a lot of starting and stopping, use MED or LOW.

The super high "water pressure" sound you hear is the HST valves bypassing under load. If the load is not too high, the tractor will accelerate and that noise will be replaced by the regular noise of the HST. There is one valve for FWD and one valve for REV. It doesn't bypass much in MED or LOW range so you don't hear it.

I just had both valves replaced under warranty as they were bypassing more than they should. I think the previous owner did everything in HIGH which probably wore them out.

The first time I drove my machine I thought the tranny was about to explode. My L-3800 and your 3901 has almost 40hp. That takes a fairly large HST to handle the loads. Big tranny=Big noise. I too hope to quiet it down some when I swap to synth fluid. (If I remember correctly, the CASE 580D backhoe I ran after college only had a 45hp motor.)

In the meantime, get some good headphones. I wear the ones with a radio built in.

Welcome.

Ray

Ray, Super helpful post and explanation. Knowing what is going on makes the noise less of an issue. Having spent 21 years in the submarine service, knowing what it is supposed to sound like is key. One of the times you get nervous on a sub is when suddenly everything gets quiet - no machinery noise. That's when you know something bad just happened.

Also good to have an explanation of the ranges. My property is mostly flat - coastal Georgia. I was driving around in high, mostly because I could. Driving up on the septic mound bogged the tractor to the point that the engine stalled. Was probably on at 1800 rpm, so I was off of the peak torque, but I will try it again using the M range and see. I also have about an acre of property that can be pretty wet during certain times of the year. Driving around last week, I was in 8-15 inches of soft ground and mud. I did have to use 4WD, but the tractor handled it well. I guess if I do get stuck, I have the FEL and BH to push/pull my way out.

 

[lescarpentier]

4 hours on it so far, so I'll wait until the 50 hour filter change. Thanks.

It's my understanding,(from the dealer), That all of the tractors are being sold now with the SuperUT2 fluid.Check with your dealer before you change it prematurely.

 

[BAP]

High range is basically a road gear. It's not intended to be used for doing work. It's for moving from place to place.

 

[Wormwood]

I used to have a L3901 & can sympathize with the whine. Sudt2 is a full synthetic & is about 3x the price. If I remember right the L3901 would take .... 7 gallons, maybe more. If you want to change the fluid @ 50hrs., that's fine but be sure & operate all the different hydraulic circuits on the tractor. this so you can clean out all the metal flashing left over from the mfg. process.

For me, the Bx25 was whiny enough but the L3901 was over the top. I eventually figured out the ROPS, being bolted so tightly to the frame & axle carried the HST whine & resonanted it, like a tuning fork around your head. I took some landscape expanding foam extended the nozzles tubes & filled the ROPS upper & lower sections with that foam. It helped but nothing would get rid of the noise completely. additionally I cut a piece of pond liner & put it where the ROPS bolted to the fender on the BX25. It seemed like that helped as well, but I can't specifically recall.

Hope this helps ya...

Wormwood

 

[fendley]

Wormwood, it does help, thanks. I have been out of town this week so I have not been able to try the suggestions in this thread, but I will today and the weekend. One of the biggest takeaways is the normalcy of the sound; now I don't have to worry that something is wrong, it is just the nature of the HST. I think shifting out of H to M for the default mode will improve things - I only have 5 acres here so it is not like I have a great distance to transport the tractor.

 

[Brazos]

It's my understanding,(from the dealer), That all of the tractors are being sold now with the SuperUT2 fluid.Check with your dealer before you change it prematurely.

My dealer also told me that all new tractors are being sold with SUTD2 fluid. So you may already have this fluid.

 

[kenmac]

My B26 got quieter as it wore in and pulls MUCH better now than when new. 196 hours now.